.SH Options for selecting a mode are:
.TP
-.BR -A ", " --assemble
+.BR \-A ", " \-\-assemble
Assemble a pre-existing array.
.TP
-.BR -B ", " --build
+.BR \-B ", " \-\-build
Build a legacy array without superblocks.
.TP
-.BR -C ", " --create
+.BR \-C ", " \-\-create
Create a new array.
.TP
-.BR -F ", " --follow ", " --monitor
+.BR \-F ", " \-\-follow ", " \-\-monitor
Select
.B Monitor
mode.
.TP
-.BR -G ", " --grow
+.BR \-G ", " \-\-grow
Change the size or shape of an active array.
.TP
-.BE -I ", " --incremental
+.BE \-I ", " \-\-incremental
Add a single device into an appropriate array, and possibly start the array.
.P
If a device is given before any options, or if the first option is
-.BR --add ,
-.BR --fail ,
+.BR \-\-add ,
+.BR \-\-fail ,
or
-.BR --remove ,
+.BR \-\-remove ,
then the MANAGE mode is assume.
Anything other than these will cause the
.B Misc
.SH Options that are not mode-specific are:
.TP
-.BR -h ", " --help
+.BR \-h ", " \-\-help
Display general help message or, after one of the above options, a
mode specific help message.
.TP
-.B --help-options
+.B \-\-help\-options
Display more detailed help about command line parsing and some commonly
used options.
.TP
-.BR -V ", " --version
+.BR \-V ", " \-\-version
Print version information for mdadm.
.TP
-.BR -v ", " --verbose
+.BR \-v ", " \-\-verbose
Be more verbose about what is happening. This can be used twice to be
extra-verbose.
The extra verbosity currently only affects
-.B --detail --scan
+.B \-\-detail \-\-scan
and
-.BR "--examine --scan" .
+.BR "\-\-examine \-\-scan" .
.TP
-.BR -q ", " --quiet
+.BR \-q ", " \-\-quiet
Avoid printing purely informative messages. With this,
.B mdadm
will be silent unless there is something really important to report.
.TP
-.BR -b ", " --brief
+.BR \-b ", " \-\-brief
Be less verbose. This is used with
-.B --detail
+.B \-\-detail
and
-.BR --examine .
+.BR \-\-examine .
Using
-.B --brief
+.B \-\-brief
with
-.B --verbose
+.B \-\-verbose
gives an intermediate level of verbosity.
.TP
-.BR -f ", " --force
+.BR \-f ", " \-\-force
Be more forceful about certain operations. See the various modes of
the exact meaning of this option in different contexts.
.TP
-.BR -c ", " --config=
+.BR \-c ", " \-\-config=
Specify the config file. Default is to use
.BR /etc/mdadm.conf ,
or if that is missing, then
will act as though the config file were empty.
.TP
-.BR -s ", " --scan
+.BR \-s ", " \-\-scan
scan config file or
.B /proc/mdstat
for missing information.
configuration file:
.BR /etc/mdadm.conf .
One exception is MISC mode when using
-.B --detail
+.B \-\-detail
or
-.B --stop
+.B \-\-stop
in which case
-.B --scan
+.B \-\-scan
says to get a list of array devices from
.BR /proc/mdstat .
.TP
-.B -e ", " --metadata=
+.B \-e ", " \-\-metadata=
Declare the style of superblock (raid metadata) to be used. The
default is 0.90 for
-.BR --create ,
+.BR \-\-create ,
and to guess for other operations.
The default can be overridden by setting the
.B metadata
.RE
.TP
-.B --homehost=
+.B \-\-homehost=
This will override any
.B HOMEHOST
setting in the config file and provides the identify of the host which
.SH For create, build, or grow:
.TP
-.BR -n ", " --raid-devices=
+.BR \-n ", " \-\-raid\-devices=
Specify the number of active devices in the array. This, plus the
number of spare devices (see below) must equal the number of
.I component-devices
(including "\fBmissing\fP" devices)
that are listed on the command line for
-.BR --create .
+.BR \-\-create .
Setting a value of 1 is probably
a mistake and so requires that
-.B --force
+.B \-\-force
be specified first. A value of 1 will then be allowed for linear,
multipath, raid0 and raid1. It is never allowed for raid4 or raid5.
.br
This number can only be changed using
-.B --grow
+.B \-\-grow
for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide
necessary support.
.TP
-.BR -x ", " --spare-devices=
+.BR \-x ", " \-\-spare\-devices=
Specify the number of spare (eXtra) devices in the initial array.
Spares can also be added
and removed later. The number of component devices listed
.TP
-.BR -z ", " --size=
+.BR \-z ", " \-\-size=
Amount (in Kibibytes) of space to use from each drive in RAID1/4/5/6.
This must be a multiple of the chunk size, and must leave about 128Kb
of space at the end of the drive for the RAID superblock.
issued.
This value can be set with
-.B --grow
+.B \-\-grow
for RAID level 1/4/5/6. If the array was created with a size smaller
than the currently active drives, the extra space can be accessed
using
-.BR --grow .
+.BR \-\-grow .
The size can be given as
.B max
which means to choose the largest size that fits on all current drives.
.TP
-.BR -c ", " --chunk=
+.BR \-c ", " \-\-chunk=
Specify chunk size of kibibytes. The default is 64.
.TP
-.BR --rounding=
+.BR \-\-rounding=
Specify rounding factor for linear array (==chunk size)
.TP
-.BR -l ", " --level=
+.BR \-l ", " \-\-level=
Set raid level. When used with
-.BR --create ,
+.BR \-\-create ,
options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4,
raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty. Obviously some of these are synonymous.
When used with
-.BR --build ,
+.BR \-\-build ,
only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid.
Not yet supported with
-.BR --grow .
+.BR \-\-grow .
.TP
-.BR -p ", " --layout=
+.BR \-p ", " \-\-layout=
This option configures the fine details of data layout for raid5,
and raid10 arrays, and controls the failure modes for
.IR faulty .
The layout of the raid5 parity block can be one of
-.BR left-asymmetric ,
-.BR left-symmetric ,
-.BR right-asymmetric ,
-.BR right-symmetric ,
+.BR left\-asymmetric ,
+.BR left\-symmetric ,
+.BR right\-asymmetric ,
+.BR right\-symmetric ,
.BR la ", " ra ", " ls ", " rs .
The default is
-.BR left-symmetric .
+.BR left\-symmetric .
When setting the failure mode for
.I faulty
the options are:
-.BR write-transient ", " wt ,
-.BR read-transient ", " rt ,
-.BR write-persistent ", " wp ,
-.BR read-persistent ", " rp ,
-.BR write-all ,
-.BR read-fixable ", " rf ,
+.BR write\-transient ", " wt ,
+.BR read\-transient ", " rt ,
+.BR write\-persistent ", " wp ,
+.BR read\-persistent ", " rp ,
+.BR write\-all ,
+.BR read\-fixable ", " rf ,
.BR clear ", " flush ", " none .
Each mode can be followed by a number which is used as a period
every time the period elapses.
Multiple failure modes can be current simultaneously by using the
-.B --grow
+.B \-\-grow
option to set subsequent failure modes.
"clear" or "none" will remove any pending or periodic failure modes,
and "flush" will clear any persistent faults.
To set the parity with
-.BR --grow ,
+.BR \-\-grow ,
the level of the array ("faulty")
must be specified before the fault mode is specified.
with an odd number of devices).
.TP
-.BR --parity=
+.BR \-\-parity=
same as
-.B --layout
+.B \-\-layout
(thus explaining the p of
-.BR -p ).
+.BR \-p ).
.TP
-.BR -b ", " --bitmap=
+.BR \-b ", " \-\-bitmap=
Specify a file to store a write-intent bitmap in. The file should not
exist unless
-.B --force
+.B \-\-force
is also given. The same file should be provided
when assembling the array. If the word
.B internal
and so is replicated on all devices. If the word
.B none
is given with
-.B --grow
+.B \-\-grow
mode, then any bitmap that is present is removed.
To help catch typing errors, the filename must contain at least one
Storing bitmap files on other filesystems may result in serious problems.
.TP
-.BR --bitmap-chunk=
+.BR \-\-bitmap\-chunk=
Set the chunksize of the bitmap. Each bit corresponds to that many
Kilobytes of storage.
When using a file based bitmap, the default is to use the smallest
.TP
-.BR -W ", " --write-mostly
+.BR \-W ", " \-\-write\-mostly
subsequent devices lists in a
-.BR --build ,
-.BR --create ,
+.BR \-\-build ,
+.BR \-\-create ,
or
-.B --add
+.B \-\-add
command will be flagged as 'write-mostly'. This is valid for RAID1
only and means that the 'md' driver will avoid reading from these
devices if at all possible. This can be useful if mirroring over a
slow link.
.TP
-.BR --write-behind=
+.BR \-\-write\-behind=
Specify that write-behind mode should be enabled (valid for RAID1
only). If an argument is specified, it will set the maximum number
of outstanding writes allowed. The default value is 256.
.IR write-mostly .
.TP
-.BR --assume-clean
+.BR \-\-assume\-clean
Tell
.I mdadm
that the array pre-existed and is known to be clean. It can be useful
recommended. Use this ony if you really know what you are doing.
.TP
-.BR --backup-file=
+.BR \-\-backup\-file=
This is needed when
-.B --grow
+.B \-\-grow
is used to increase the number of
raid-devices in a RAID5 if there are no spare devices available.
See the section below on RAID_DEVICE CHANGES. The file should be
stored on a separate device, not on the raid array being reshaped.
.TP
-.BR -N ", " --name=
+.BR \-N ", " \-\-name=
Set a
.B name
for the array. This is currently only effective when creating an
string that can be used to identify array components when assembling.
.TP
-.BR -R ", " --run
+.BR \-R ", " \-\-run
Insist that
.I mdadm
run the array, even if some of the components
array. This option causes that question to be suppressed.
.TP
-.BR -f ", " --force
+.BR \-f ", " \-\-force
Insist that
.I mdadm
accept the geometry and layout specified without question. Normally
will not allow creation of an array with only one device, and will try
to create a raid5 array with one missing drive (as this makes the
initial resync work faster). With
-.BR --force ,
+.BR \-\-force ,
.I mdadm
will not try to be so clever.
.TP
-.BR -a ", " "--auto{=no,yes,md,mdp,part,p}{NN}"
+.BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}"
Instruct mdadm to create the device file if needed, possibly allocating
an unused minor number. "md" causes a non-partitionable array
to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and
from this. See DEVICE NAMES below.
The argument can also come immediately after
-"-a". e.g. "-ap".
+"\-a". e.g. "\-ap".
If
-.B --auto
+.B \-\-auto
is not given on the command line or in the config file, then
the default will be
-.BR --auto=yes .
+.BR \-\-auto=yes .
If
-.B --scan
+.B \-\-scan
is also given, then any
.I auto=
entries in the config file will override the
-.B --auto
+.B \-\-auto
instruction given on the command line.
For partitionable arrays,
will create the device file for the whole array and for the first 4
partitions. A different number of partitions can be specified at the
end of this option (e.g.
-.BR --auto=p7 ).
+.BR \-\-auto=p7 ).
If the device name ends with a digit, the partition names add a 'p',
and a number, e.g. "/dev/home1p3". If there is no
trailing digit, then the partition names just have a number added,
non-standard name.
.TP
-.BR --symlink = no
+.BR \-\-symlink = no
Normally when
-.B --auto
+.B \-\-auto
causes
.I mdadm
to create devices in
or
.BR md_ .
Use
-.B --symlink=no
+.B \-\-symlink=no
to suppress this, or
-.B --symlink=yes
+.B \-\-symlink=yes
to enforce this even if it is suppressing
.IR mdadm.conf .
.SH For assemble:
.TP
-.BR -u ", " --uuid=
+.BR \-u ", " \-\-uuid=
uuid of array to assemble. Devices which don't have this uuid are
excluded
.TP
-.BR -m ", " --super-minor=
+.BR \-m ", " \-\-super\-minor=
Minor number of device that array was created for. Devices which
don't have this minor number are excluded. If you create an array as
/dev/md1, then all superblocks will contain the minor number 1, even if
the array is later assembled as /dev/md2.
Giving the literal word "dev" for
-.B --super-minor
+.B \-\-super\-minor
will cause
.I mdadm
to use the minor number of the md device that is being assembled.
e.g. when assembling
.BR /dev/md0 ,
-.M --super-minor=dev
+.M \-\-super\-minor=dev
will look for super blocks with a minor number of 0.
.TP
-.BR -N ", " --name=
+.BR \-N ", " \-\-name=
Specify the name of the array to assemble. This must be the name
that was specified when creating the array. It must either match
then name stored in the superblock exactly, or it must match
is added to the start of the given name.
.TP
-.BR -f ", " --force
+.BR \-f ", " \-\-force
Assemble the array even if some superblocks appear out-of-date
.TP
-.BR -R ", " --run
+.BR \-R ", " \-\-run
Attempt to start the array even if fewer drives were given than were
present last time the array was active. Normally if not all the
expected drives are found and
-.B --scan
+.B \-\-scan
is not used, then the array will be assembled but not started.
With
-.B --run
+.B \-\-run
an attempt will be made to start it anyway.
.TP
-.B --no-degraded
+.B \-\-no\-degraded
This is the reverse of
-.B --run
+.B \-\-run
in that it inhibits the started if array unless all expected drives
are present. This is only needed with
-.B --scan
+.B \-\-scan
and can be used if you physical connections to devices are
not as reliable as you would like.
.TP
-.BR -a ", " "--auto{=no,yes,md,mdp,part}"
+.BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}"
See this option under Create and Build options.
.TP
-.BR -b ", " --bitmap=
+.BR \-b ", " \-\-bitmap=
Specify the bitmap file that was given when the array was created. If
an array has an
.B internal
bitmap, there is no need to specify this when assembling the array.
.TP
-.BR --backup-file=
+.BR \-\-backup\-file=
If
-.B --backup-file
+.B \-\-backup\-file
was used to grow the number of raid-devices in a RAID5, and the system
crashed during the critical section, then the same
-.B --backup-file
+.B \-\-backup\-file
must be presented to
-.B --assemble
+.B \-\-assemble
to allow possibly corrupted data to be restored.
.TP
-.BR -U ", " --update=
+.BR \-U ", " \-\-update=
Update the superblock on each device while assembling the array. The
argument given to this flag can be one of
.BR sparc2.2 ,
.BR byteorder ,
.BR devicesize ,
or
-.BR super-minor .
+.BR super\-minor .
The
.B sparc2.2
option will adjust the superblock of an array what was created on a Sparc
machine running a patched 2.2 Linux kernel. This kernel got the
alignment of part of the superblock wrong. You can use the
-.B "--examine --sparc2.2"
+.B "\-\-examine \-\-sparc2.2"
option to
.I mdadm
to see what effect this would have.
The
-.B super-minor
+.B super\-minor
option will update the
.B "preferred minor"
field on each superblock to match the minor number of the array being
assembled.
This can be useful if
-.B --examine
+.B \-\-examine
reports a different "Preferred Minor" to
-.BR --detail .
+.BR \-\-detail .
In some cases this update will be performed automatically
by the kernel driver. In particular the update happens automatically
at the first write to an array with redundancy (RAID level 1 or
The
.B uuid
option will change the uuid of the array. If a UUID is given with the
-.B --uuid
+.B \-\-uuid
option that UUID will be used as a new UUID and will
.B NOT
be used to help identify the devices in the array.
If no
-.B --uuid
+.B \-\-uuid
is given, a random UUID is chosen.
The
option allows arrays to be moved between machines with different
byte-order.
When assembling such an array for the first time after a move, giving
-.B "--update=byteorder"
+.B "\-\-update=byteorder"
will cause
.I mdadm
to expect superblocks to have their byteorder reversed, and will
array becomes larger, the metadata will still be visible, but the
extra space will not. In this case it might be useful to assemble the
array with
-.BR --update=devicesize .
+.BR \-\-update=devicesize .
This will cause
.I mdadm
to determine the maximum usable amount of space on each device and
update the relevant field in the metadata.
.TP
-.B --auto-update-homehost
+.B \-\-auto\-update\-homehost
This flag is only meaning with auto-assembly (see discussion below).
In that situation, if no suitable arrays are found for this homehost,
.I mdadm
.SH For Manage mode:
.TP
-.BR -a ", " --add
+.BR \-a ", " \-\-add
hot-add listed devices.
.TP
-.BR --re-add
+.BR \-\-re\-add
re-add a device that was recently removed from an array.
.TP
-.BR -r ", " --remove
+.BR \-r ", " \-\-remove
remove listed devices. They must not be active. i.e. they should
be failed or spare devices.
.TP
-.BR -f ", " --fail
+.BR \-f ", " \-\-fail
mark listed devices as faulty.
.TP
-.BR --set-faulty
+.BR \-\-set\-faulty
same as
-.BR --fail .
+.BR \-\-fail .
.P
Each of these options require that the first device list is the array
removed, or marked as fault. Several different operations can be
specified for different devices, e.g.
.in +5
-mdadm /dev/md0 --add /dev/sda1 --fail /dev/sdb1 --remove /dev/sdb1
+mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1
.in -5
Each operation applies to all devices listed until the next
operations.
reconstruction but instead just updated the blocks that have changed
since the device was removed. For arrays with persistent metadata
(superblocks) this is done automatically. For arrays created with
-.B --build
+.B \-\-build
mdadm needs to be told that this device we removed recently with
-.BR --re-add .
+.BR \-\-re\-add .
Devices can only be removed from an array if they are not in active
use. i.e. that must be spares or failed devices. To remove an active
.SH For Misc mode:
.TP
-.BR -Q ", " --query
+.BR \-Q ", " \-\-query
Examine a device to see
(1) if it is an md device and (2) if it is a component of an md
array.
Information about what is discovered is presented.
.TP
-.BR -D ", " --detail
+.BR \-D ", " \-\-detail
Print detail of one or more md devices.
.TP
-.BR -E ", " --examine
+.BR \-E ", " \-\-examine
Print content of md superblock on device(s).
.TP
-.B --sparc2.2
+.B \-\-sparc2.2
If an array was created on a 2.2 Linux kernel patched with RAID
support, the superblock will have been created incorrectly, or at
least incompatibly with 2.4 and later kernels. Using the
-.B --sparc2.2
+.B \-\-sparc2.2
flag with
-.B --examine
+.B \-\-examine
will fix the superblock before displaying it. If this appears to do
the right thing, then the array can be successfully assembled using
-.BR "--assemble --update=sparc2.2" .
+.BR "\-\-assemble \-\-update=sparc2.2" .
.TP
-.BR -X ", " --examine-bitmap
+.BR \-X ", " \-\-examine\-bitmap
Report information about a bitmap file.
.TP
-.BR -R ", " --run
+.BR \-R ", " \-\-run
start a partially built array.
.TP
-.BR -S ", " --stop
+.BR \-S ", " \-\-stop
deactivate array, releasing all resources.
.TP
-.BR -o ", " --readonly
+.BR \-o ", " \-\-readonly
mark array as readonly.
.TP
-.BR -w ", " --readwrite
+.BR \-w ", " \-\-readwrite
mark array as readwrite.
.TP
-.B --zero-superblock
+.B \-\-zero\-superblock
If the device contains a valid md superblock, the block is
overwritten with zeros. With
-.B --force
+.B \-\-force
the block where the superblock would be is overwritten even if it
doesn't appear to be valid.
.TP
-.BR -t ", " --test
+.BR \-t ", " \-\-test
When used with
-.BR --detail ,
+.BR \-\-detail ,
the exit status of
.I mdadm
is set to reflect the status of the device.
.TP
-.BR -W ", " --wait
+.BR \-W ", " \-\-wait
For each md device given, wait for any resync, recovery, or reshape
activity to finish before returning.
.I mdadm
.SH For Incremental Assembly mode:
.TP
-.BR --rebuild-map ", " -r
+.BR \-\-rebuild\-map ", " \-r
Rebuild the map file
.RB ( /var/run/mdadm/map )
that
uses to help track which arrays are currently being assembled.
.TP
-.BR --run ", " -R
+.BR \-\-run ", " \-R
Run any array assembled as soon as a minimal number of devices are
available, rather than waiting until all expected devices are present.
.TP
-.BR --scan ", " -s
+.BR \-\-scan ", " \-s
Only meaningful with
-.B -R
+.B \-R
this will scan the
.B map
file for arrays that are being incrementally assembled and will try to
.SH For Monitor mode:
.TP
-.BR -m ", " --mail
+.BR \-m ", " \-\-mail
Give a mail address to send alerts to.
.TP
-.BR -p ", " --program ", " --alert
+.BR \-p ", " \-\-program ", " \-\-alert
Give a program to be run whenever an event is detected.
.TP
-.BR -y ", " --syslog
+.BR \-y ", " \-\-syslog
Cause all events to be reported through 'syslog'. The messages have
facility of 'daemon' and varying priorities.
.TP
-.BR -d ", " --delay
+.BR \-d ", " \-\-delay
Give a delay in seconds.
.B mdadm
polls the md arrays and then waits this many seconds before polling
again. The default is 60 seconds.
.TP
-.BR -f ", " --daemonise
+.BR \-f ", " \-\-daemonise
Tell
.B mdadm
to run as a background daemon if it decides to monitor anything. This
causes it to fork and run in the child, and to disconnect form the
terminal. The process id of the child is written to stdout.
This is useful with
-.B --scan
+.B \-\-scan
which will only continue monitoring if a mail address or alert program
is found in the config file.
.TP
-.BR -i ", " --pid-file
+.BR \-i ", " \-\-pid\-file
When
.B mdadm
is running in daemon mode, write the pid of the daemon process to
the specified file, instead of printing it on standard output.
.TP
-.BR -1 ", " --oneshot
+.BR \-1 ", " \-\-oneshot
Check arrays only once. This will generate
.B NewArray
events and more significantly
.B SparesMissing
events. Running
.in +5
-.B " mdadm --monitor --scan -1"
+.B " mdadm \-\-monitor \-\-scan \-1"
.in -5
from a cron script will ensure regular notification of any degraded arrays.
.TP
-.BR -t ", " --test
+.BR \-t ", " \-\-test
Generate a
.B TestMessage
alert for every array found at startup. This alert gets mailed and
.HP 12
Usage:
-.B mdadm --assemble
+.B mdadm \-\-assemble
.I md-device options-and-component-devices...
.HP 12
Usage:
-.B mdadm --assemble --scan
+.B mdadm \-\-assemble \-\-scan
.I md-devices-and-options...
.HP 12
Usage:
-.B mdadm --assemble --scan
+.B mdadm \-\-assemble \-\-scan
.I options...
.PP
array, and a number of component-devices. These can be found in a number of ways.
In the first usage example (without the
-.BR --scan )
+.BR \-\-scan )
the first device given is the md device.
In the second usage example, all devices listed are treated as md
devices and assembly is attempted.
listed in the configuration file are assembled.
If precisely one device is listed, but
-.B --scan
+.B \-\-scan
is not given, then
.I mdadm
acts as though
-.B --scan
+.B \-\-scan
was given and identify information is extracted from the configuration file.
The identity can be given with the
-.B --uuid
+.B \-\-uuid
option, with the
-.B --super-minor
+.B \-\-super\-minor
option, can be found in the config file, or will be taken from the
super block on the first component-device listed on the command line.
Devices can be given on the
-.B --assemble
+.B \-\-assemble
command line or in the config file. Only devices which have an md
superblock which contains the right identity will be considered for
any array.
The config file is only used if explicitly named with
-.B --config
+.B \-\-config
or requested with (a possibly implicit)
-.BR --scan .
+.BR \-\-scan .
In the later case,
.B /etc/mdadm.conf
is used.
If
-.B --scan
+.B \-\-scan
is not given, then the config file will only be used to find the
identity of md arrays.
Normally the array will be started after it is assembled. However if
-.B --scan
+.B \-\-scan
is not given and insufficient drives were listed to start a complete
(non-degraded) array, then the array is not started (to guard against
usage errors). To insist that the array be started in this case (as
may work for RAID1, 4, 5, 6, or 10), give the
-.B --run
+.B \-\-run
flag.
If the md device does not exist, then it will be created providing the
intent is clear. i.e. the name must be in a standard form, or the
-.B --auto
+.B \-\-auto
option must be given to clarify how and whether the device should be
created.
ends with a digit.
The
-.B --auto
+.B \-\-auto
option is also available in Build and Create modes. As those modes do
not use a config file, the "auto=" config option does not apply to
these modes.
.SS Auto Assembly
When
-.B --assemble
+.B \-\-assemble
is used with
-.B --scan
+.B \-\-scan
and no devices are listed,
.I mdadm
will first attempt to assemble all the arrays listed in the config
If
.I mdadm
cannot find any array for the given host at all, and if
-.B --auto-update-homehost
+.B \-\-auto\-update\-homehost
is given, then
.I mdadm
will search again for any array (not just an array created for this
host) and will assemble each assuming
-.BR --update=homehost .
+.BR \-\-update=homehost .
This will change the host tag in the superblock so that on the next run,
these arrays will be found without the second pass. The intention of
this feature is to support transitioning a set of md arrays to using
.HP 12
Usage:
-.B mdadm --build
+.B mdadm \-\-build
.I device
-.BI --chunk= X
-.BI --level= Y
-.BI --raid-devices= Z
+.BI \-\-chunk= X
+.BI \-\-level= Y
+.BI \-\-raid\-devices= Z
.I devices
.PP
This usage is similar to
-.BR --create .
+.BR \-\-create .
The difference is that it creates an array without a superblock. With
these arrays there is no difference between initially creating the array and
subsequently assembling the array, except that hopefully there is useful
.HP 12
Usage:
-.B mdadm --create
+.B mdadm \-\-create
.I device
-.BI --chunk= X
-.BI --level= Y
+.BI \-\-chunk= X
+.BI \-\-level= Y
.br
-.BI --raid-devices= Z
+.BI \-\-raid\-devices= Z
.I devices
.PP
it, and activate the array.
If the
-.B --auto
+.B \-\-auto
option is given (as described in more detail in the section on
Assemble mode), then the md device will be created with a suitable
device number if necessary.
If any discrepancy is found, the array will not automatically be run, though
the presence of a
-.B --run
+.B \-\-run
can override this caution.
To create a "degraded" array in which some devices are missing, simply
This is because building the spare into a degraded array is in general faster than resyncing
the parity on a non-degraded, but not clean, array. This feature can
be overridden with the
-.B --force
+.B \-\-force
option.
When creating an array with version-1 metadata a name for the host is
required.
If this is not given with the
-.B --name
+.B \-\-name
option,
.I mdadm
will chose a name based on the last component of the name of the
A new array will normally get a randomly assigned 128bit UUID which is
very likely to be unique. If you have a specific need, you can choose
a UUID for the array by giving the
-.B --uuid=
+.B \-\-uuid=
option. Be warned that creating two arrays with the same UUID is a
recipe for disaster. Also, using
-.B --uuid=
+.B \-\-uuid=
when creating a v0.90 array will silently override any
-.B --homehost=
+.B \-\-homehost=
setting.
'''If the
-'''.B --size
+'''.B \-\-size
'''option is given, it is not necessary to list any component-devices in this command.
'''They can be added later, before a
-'''.B --run.
+'''.B \-\-run.
'''If no
-'''.B --size
+'''.B \-\-size
'''is given, the apparent size of the smallest drive given is used.
The General Management options that are valid with
-.B --create
+.B \-\-create
are:
.TP
-.B --run
+.B \-\-run
insist on running the array even if some devices look like they might
be in use.
.TP
-.B --readonly
+.B \-\-readonly
start the array readonly \(em not supported yet.
removed or added. It is possible to perform multiple operations with
on command. For example:
.br
-.B " mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"
+.B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1"
.br
will firstly mark
.B /dev/hda1
MISC mode includes a number of distinct operations that
operate on distinct devices. The operations are:
.TP
---query
+\-\-query
The device is examined to see if it is
(1) an active md array, or
(2) a component of an md array.
The information discovered is reported.
.TP
---detail
+\-\-detail
The device should be an active md device.
.B mdadm
will display a detailed description of the array.
-.B --brief
+.B \-\-brief
or
-.B --scan
+.B \-\-scan
will cause the output to be less detailed and the format to be
suitable for inclusion in
.BR /etc/mdadm.conf .
will normally be 0 unless
.I mdadm
failed to get useful information about the device(s). However if the
-.B --test
+.B \-\-test
option is given, then the exit status will be:
.RS
.TP
.RE
.TP
---examine
+\-\-examine
The device should be a component of an md array.
.B mdadm
will read the md superblock of the device and display the contents.
If
-.B --brief
+.B \-\-brief
is given, or
-.B --scan
+.B \-\-scan
then multiple devices that are components of the one array
are grouped together and reported in a single entry suitable
for inclusion in
.BR /etc/mdadm.conf .
Having
-.B --scan
+.B \-\-scan
without listing any devices will cause all devices listed in the
config file to be examined.
.TP
---stop
+\-\-stop
The devices should be active md arrays which will be deactivated, as
long as they are not currently in use.
.TP
---run
+\-\-run
This will fully activate a partially assembled md array.
.TP
---readonly
+\-\-readonly
This will mark an active array as read-only, providing that it is
not currently being used.
.TP
---readwrite
+\-\-readwrite
This will change a
.B readonly
array back to being read/write.
.TP
---scan
+\-\-scan
For all operations except
-.BR --examine ,
-.B --scan
+.BR \-\-examine ,
+.B \-\-scan
will cause the operation to be applied to all arrays listed in
.BR /proc/mdstat .
For
-.BR --examine,
-.B --scan
+.BR \-\-examine,
+.B \-\-scan
causes all devices listed in the config file to be examined.
.HP 12
Usage:
-.B mdadm --monitor
+.B mdadm \-\-monitor
.I options... devices...
.PP
.B mdadm
will only monitor those devices. Otherwise all arrays listed in the
configuration file will be monitored. Further, if
-.B --scan
+.B \-\-scan
is given, then any other md devices that appear in
.B /proc/mdstat
will also be monitored.
device if relevant, such as a component device that has failed.
If
-.B --scan
+.B \-\-scan
is given, then a program or an E-mail address must be specified on the
command line or in the config file. If neither are available, then
.B mdadm
will not monitor anything.
Without
-.B --scan
+.B \-\-scan
.B mdadm
will continue monitoring as long as something was found to monitor. If
no program or email is given, then each event is reported to
.TP
.B TestMessage
An array was found at startup, and the
-.B --test
+.B \-\-test
flag was given.
(syslog priority: Info)
.RE
that is in that section. This backup is normally stored in any spare
devices that the array has, however it can also be stored in a
separate file specified with the
-.B --backup-file
+.B \-\-backup\-file
option. If this option is used, and the system does crash during the
critical period, the same file must be passed to
-.B --assemble
+.B \-\-assemble
to restore the backup and reassemble the array.
.SS BITMAP CHANGES
.HP 12
Usage:
-.B mdadm --incremental
-.RB [ --run ]
-.RB [ --quiet ]
+.B mdadm \-\-incremental
+.RB [ \-\-run ]
+.RB [ \-\-quiet ]
.I component-device
.HP 12
Usage:
-.B mdadm --incremental --rebuild
+.B mdadm \-\-incremental \-\-rebuild
.HP 12
Usage:
-.B mdadm --incremental --run --scan
+.B mdadm \-\-incremental \-\-run \-\-scan
.PP
This mode is designed to be used in conjunction with a device
discovery system. As devices are found in a system, they can be
passed to
-.B "mdadm --incremental"
+.B "mdadm \-\-incremental"
to be conditionally added to an appropriate array.
.I mdadm
(active or spare) parts of that array. It does not currently support
automatic inclusion of a new drive as a spare in some array.
-.B "mdadm --incremental"
+.B "mdadm \-\-incremental"
requires a bug present in all kernels through 2.6.19, to be fixed.
Hopefully this will be fixed in 2.6.20. Alternately apply the patch
which is included with the mdadm source distribution. If
.I mdadm
detects that this bug is present, it will abort any attempt to use
-.BR --incremental .
+.BR \-\-incremental .
The tests that
.I mdadm
.IP +
Does the device have a valid md superblock. If a specific metadata
version is request with
-.B --metadata
+.B \-\-metadata
or
-.B -e
+.B \-e
then only that style of metadata is accepted, otherwise
.I mdadm
finds any known version of metadata. If no
that if any devices are missing the array will not be restarted.
As an alternative,
-.B --run
+.B \-\-run
may be passed to
.B mdadm
in which case the array will be run as soon as there are enough
Note that neither of these approaches is really ideal. If it is can
be known that all device discovery has completed, then
.br
-.B " mdadm -IRs"
+.B " mdadm \-IRs"
.br
can be run which will try to start all arrays that are being
incrementally assembled. They are started in "read-auto" mode in
.SH EXAMPLES
-.B " mdadm --query /dev/name-of-device"
+.B " mdadm \-\-query /dev/name-of-device"
.br
This will find out if a given device is a raid array, or is part of
one, and will provide brief information about the device.
-.B " mdadm --assemble --scan"
+.B " mdadm \-\-assemble \-\-scan"
.br
This will assemble and start all arrays listed in the standard config file
file. This command will typically go in a system startup file.
-.B " mdadm --stop --scan"
+.B " mdadm \-\-stop \-\-scan"
.br
This will shut down all array that can be shut down (i.e. are not
currently in use). This will typically go in a system shutdown script.
-.B " mdadm --follow --scan --delay=120"
+.B " mdadm \-\-follow \-\-scan \-\-delay=120"
.br
If (and only if) there is an Email address or program given in the
standard config file, then
monitor the status of all arrays listed in that file by
polling them ever 2 minutes.
-.B " mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hd[ac]1"
+.B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1"
.br
Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1.
.br
-.B " echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > mdadm.conf"
+.B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf"
.br
-.B " mdadm --detail --scan >> mdadm.conf"
+.B " mdadm \-\-detail \-\-scan >> mdadm.conf"
.br
This will create a prototype config file that describes currently
active arrays that are known to be made from partitions of IDE or SCSI drives.
This file should be reviewed before being used as it may
contain unwanted detail.
-.B " echo 'DEVICE /dev/hd[a-z] /dev/sd*[a-z]' > mdadm.conf"
+.B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf"
.br
-.B " mdadm --examine --scan --config=mdadm.conf >> mdadm.conf"
+.B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf"
.ber
This will find what arrays could be assembled from existing IDE and
SCSI whole drives (not partitions) and store the information is the
entries. It should be reviewed and edited before being used as an
actual config file.
-.B " mdadm --examine --brief --scan --config=partitions"
+.B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions"
.br
-.B " mdadm -Ebsc partitions"
+.B " mdadm \-Ebsc partitions"
.br
Create a list of devices by reading
.BR /proc/partitions ,
scan these for RAID superblocks, and printout a brief listing of all
that was found.
-.B " mdadm -Ac partitions -m 0 /dev/md0"
+.B " mdadm \-Ac partitions \-m 0 /dev/md0"
.br
Scan all partitions and devices listed in
.BR /proc/partitions
.B /dev/md0
out of all such devices with a RAID superblock with a minor number of 0.
-.B " mdadm --monitor --scan --daemonise > /var/run/mdadm"
+.B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm"
.br
If config file contains a mail address or alert program, run mdadm in
the background in monitor mode monitoring all md devices. Also write
pid of mdadm daemon to
.BR /var/run/mdadm .
-.B " mdadm -Iq /dev/somedevice"
+.B " mdadm \-Iq /dev/somedevice"
.br
Try to incorporate newly discovered device into some array as
appropriate.
-.B " mdadm --incremental --rebuild --run --scan"
+.B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan"
.br
Rebuild the array map from any current arrays, and then start any that
can be started.
-.B " mdadm --create --help"
+.B " mdadm \-\-create \-\-help"
.br
Provide help about the Create mode.
-.B " mdadm --config --help"
+.B " mdadm \-\-config \-\-help"
.br
Provide help about the format of the config file.
-.B " mdadm --help"
+.B " mdadm \-\-help"
.br
Provide general help.
lists all active md devices with information about them.
.B mdadm
uses this to find arrays when
-.B --scan
+.B \-\-scan
is given in Misc mode, and to monitor array reconstruction
on Monitor mode.
.SS /var/run/mdadm/map
When
-.B --incremental
+.B \-\-incremental
mode is used. this file gets a list of arrays currently being created.
If
.B /var/run/mdadm
.I mdadm
has an understanding of 'standard' formats which it uses to guide its
behaviour when creating device files via the
-.B --auto
+.B \-\-auto
option.
The standard names for non-partitioned arrays (the only sort of md
RAID, check out:
.IP
-.UR http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/
-http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/
+.UR http://ostenfeld.dk/~jakob/Software\-RAID.HOWTO/
+http://ostenfeld.dk/~jakob/Software\-RAID.HOWTO/
.UE
'''.PP
'''for new releases of the RAID driver check out:
projects / thirdparty / mdadm.git / commitdiff
